CRF50 stumble at high RPM. Need advice

Hey, everybody. I have a 2006 CRF50 that I just put back together. Thoroughly cleaned the carb, it idles well, power comes on fine in neutral. However, usually in high 2nd to mid to high 3rd, it will stutter from time to time and have a decrease in power. Is this more than likely a jetting issue?

Are there any mods to it like pipe or intake? Or is it stock. If its stock, then I would try cleaning the main jet one more time. (What I usually do to clean jets is take a single strand/braid of brake wire or something like that and go to town) If there are mods then I would probably 1. Take a look at the main jet. And if the problem is still there then 2. Think about going up a size on the main jet

The only non stock part would be a cheap uni air filter. I'll try cleaning again. Probably order a jet kit just in case. Will update. Thanks for the response.

Yeah the UNI Air Filter will do it. I'd probably say that your main jet is a little lean

double check the ground wire and ensure it is tight.  its the one above the filter that bolts on at the bottom of the main tube.  i had a similar situation after a rebuild and same symptoms you describe.  the loose connection will create that stutter from time to time if the connections is loose.  also check for tight connections at the CDI and that the connections are all clean.


bike should be rejetted, but a jetting issue will cause a stutter every time. one thing you said is that it is from time to time.

Yeah I agree with Big Red. The more I think about it the more it sounds like an electrical issue. Pretty much everything Big Red said. Spark plug cap, ground wire connection, CDI box connections, and things like that.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now